Chain Tensioner for Dedicated Trainer Bike

So I have a direct drive trainer and picked up a spare frame for a dedicated trainer bike. I had enough parts to just about have it ready to go, except a rear derailleur. I only need it for ERG, so I don’t need to shift. Options I can think of are:

  • buy a cheap mechanical RD and use an old cable to set it in the gear I want.
  • buy a single speed chain tensioner
  • maybe this? (SHIMANO ALFINE Double Pulley Chain Tensioner | SHIMANO BIKE-US) not sure it will work. I have a Wolf Tooth road link laying around I could throw on to clear a bigger gear.
  • other options I’m not thinking of?

Edit: or just wrap the chain on the gear I want and try to get the length close. I’m not shifting and the bike isn’t moving. Should work?

All those options are good, but I would not run a pure chain without some form of tension. Without a tension option, you may fight installing or removing the bike from the trainer if/when needed (especially if you size the chain to minimize slack).

The old RD or the Shimano tensioner all work well. I’ve used or had friends use them with great success.

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